Device to capture relative position of a component of which the position can change relative to a reference component of a washing handling device, and corresponding washing handling device

ABSTRACT

A sensor device to measure a force or pressure in a washing handling apparatus includes a light source, a light receiver, a light-reflecting surface that reflects light emitted by the light source toward the light receiver, and one or more spring elements that biases the light-reflecting surface into a predefined initial position with respect to the light source and the light receiver where the light-reflecting surface is disposed to be displaceable with respect to the light source and the light receiver in response to application of an external force or pressure against a resetting force of the one or more spring elements.

BACKGROUND OF THE INVENTION

This invention concerns a device to capture the relative position of acomponent of which the position can change relative to a referencecomponent of a washing handling device, in particular a washing machineor drier, and a corresponding washing handling device.

Such devices are known in various forms from the prior art. Thus thedocument DE 101 04 682 A1 shows a capacitive sensor, with which theaxial distance of a tub relative to the housing of a washing machine isprovided for the purpose of determining an imbalance, deflection inoperation and the present loading of the washing drum. This solution hasthe disadvantage that capacitive sensors, in the context of thedistances to be measured, are relatively difficult to evaluate, and arealso subject to electromagnetic interference effects of the environment.

Another arrangement is known from the document DE 103 34 572 B3. In thecase of the arrangement described in this document, a coil-basedelectromagnetic travel sensor is used to capture the deflection of thetub relative to the housing. Such electromagnetic travel sensors too aresubject to interference effects and wear problems.

The document DE 698 07 055 T3 describes a washing machine where thepresent drum deflection and loading are determined using a Hall elementand a magnet body associated with it. In this case, there is the problemthat Hall sensors too are subject to electromagnetic interference, andto obtain sufficiently good measurement results, large, homogeneousmagnets are required. Use of Hall sensors also has the disadvantage thatto determine the present position in space, 3 field vectors are alwaysrequired. Use of a single dipole magnet is not enough, since its fieldcomponent is not biunique.

In the document DE 199 60 847 A1, the possibility of using strain gaugesto determine the position of the tub in the housing of a washing machineis described. To evaluate the signals provided by strain gauges,relatively expensive and sensitive amplifier and compensation circuitsare required.

The document DE 10 2004 043 752 B4 describes a measuring device withoptical sensors to determine the present deflection of an axis ofrotation of a washing drum relative to the tub of a washing machine. Theoptical system described in it has the disadvantage that it must beintegrated into the bearing arrangement of the drum, and this isstructurally expensive.

SUMMARY OF THE INVENTION

In contrast, it is the object of this invention to provide a devicewhich is of the type described above, is structurally simple, isinsensitive to external influences in operation, and has highmeasurement precision.

This object is achieved by a device to capture the relative position ofa component of which the position can change relative to a referencecomponent of a washing handling device, in particular a washing machineor drier, comprising:

-   -   at least one light source,    -   at least one light receiver,    -   a light-reflecting surface, which reflects light which the light        source emits to the light receiver,        the device being designed to capture the present relative        position, or the distance of the changeable-position component,        relative to the reference component, according to the reflected        light which the light receiver captures.

According to the invention, the position of the changeable-positioncomponent, e.g. the tub of the washing handling device, relative to thereference component, e.g. the housing of the washing handling device ora component which is arranged in a fixed position in the washinghandling device, is determined purely optically on the basis of thelight reflection and the light intensity which is captured from it. Thereflecting surface can be a surface of a separate component, or beintegrated into an existing component, e.g. a tub. Such opticaldetermination of position is possible using relatively inexpensivelyavailable components. It is not subject to any electromagneticinterference effects. No mechanical components which are moved relativeto each other, and can be subject to wear, are required. By suitableformation of the beam path or reflection path or reflecting surfaces,permanently reliable results can be achieved. Thus reflection patterns,e.g. a kind of reflection grid of reflecting and non-reflecting areas,can be used. It is also possible to use convexly or concavely curvedreflecting surfaces, in particular spherically curved reflectingsurfaces. Similarly, it is also possible to use stepped reflectingsurfaces, or ones which are alternately convexly and concavely curved insub-regions, e.g. for generating Fresnel structures, which make distancemeasurement easier.

A further development of the invention provides that the reflectingsurface is in the form of a scattering reflecting surface, whichreflects and scatters the light which the light source emits.

According to the invention, it can also be provided that the lightsource is in the form of a light-emitting diode (LED), a laser diode oran infrared light source or similar. It is also possible to arrange thelight source at a greater distance from the measuring point, and toguide the light to the measuring point via an optical waveguide.According to the invention, it can also be provided that the lightreceiver is in the form of a phototransistor, photodiode, photoresistor,passively operated LED or similar. Such light sources and lightreceivers are available inexpensively.

By pulsed control of the light source and/or light receiver,interference effects by external light can be determined and filteredout. Polarised light can also be used.

To simplify the structure of the solution according to the invention, itcan be provided that at least one pair of light source and lightreceiver are combined next to each other in one module. Here it must bestated that the measured distance is always greater than the distance oflight source and light receiver which are arranged next to each other.

In relation to this, according to a further development of theinvention, it can be provided that at least two pairs of light sourceand light receiver, which are arranged at different alignments to eachother, are arranged. It is thus possible to arrange such modules ofpairs of light source and light receiver at different positions or/andwith different alignment in the washing handling device, and thus tocapture reliably relative movements between the changeable-positioncomponent and the reference component, in particular with reference tothe housing, along different spatial axes.

According to the invention, it can also be provided that around a lightsource, multiple receivers are arranged, e.g. on two sides of the lightsource, or at regular angular distances around the light source, e.g. atan angular distance of 120°. In this way it is possible to improve thedetermination of position, e.g. by capturing a relative tilt. It is alsopossible to compensate for measurement errors. In this way, positionscan also be captured more easily in three dimensions.

According to the invention, it can also be provided that thelight-reflecting surfaces are arranged at an angle to each other. It isthus possible to provide two or three pairs of light source and lightreceiver, in a perpendicular arrangement to each other, and fixed in thehousing, and to assign reflecting surfaces which are correspondinglyperpendicularly aligned to each other to them. In this way, movementswhich are orthogonal to the reflecting surfaces can be determined.

Additionally, according to a further development of the invention, itcan be provided that the distance of the pairs of light source and lightreceiver relative to the light-reflecting surface assigned to them isdifferent. In other words, a pair of light source and light receiver canbe arranged in an initial state at a first distance from thelight-reflecting surface assigned to them, and another pair of lightsource and light receiver can be arranged in an initial state at asecond distance from the light-reflecting surface assigned to them, thetwo light-reflecting surfaces being coupled to each other. In this way,when the light reflection which the two light receivers determine isevaluated, on the basis of the known difference of distance between thefirst and second distances, a plausibility check and compensation of themeasurement result can be carried out. Preferably, the orientations ofthe two pairs of light source and light receiver are essentiallyaligned.

An alternative version of the invention provides that instead of usingmultiple light sources, the light which a single light source emits isdivided via a beam splitter, e.g. a prism or double-hole screen, intomultiple light beams or pencils of rays, and radiated onto differentlight-reflecting surfaces at different distances or/and differentalignments to the light source. The evaluation can then take place viacorresponding light receivers, in the manner described above, and withthe advantages described above.

To measure pressure or force in a washing handling device, according tothe invention a spring arrangement, which is arranged so that itprestresses at least one pair of light source and light receiver and thelight-reflecting surface into a predetermined initial position relativeto each other, and is deformed on deflection, can also be provided. Onthe basis of the captured pressure or captured force and of the distancewhich changes depending on the pressure or force, for example thefullness of a washing drum with water can be determined.

On the basis of the captured force (weight) which is exerted by a loadof washing on a drum or tub or its suspension, for example the quantityor mass of introduced washing can also be determined.

The invention also concerns a washing handling device, in particular awashing machine or drier, comprising:

-   -   a housing,    -   a changeable-position component, which is carried movably in the        housing, and    -   a device of the kind described above,        wherein on one component out of housing or changeable-position        component, a sensor arrangement with at least one pair of light        source and light receiver is arranged, and on the other        component out of housing and changeable-position component, the        light-reflecting surface is arranged, and the present relative        position of the changeable-position component relative to the        housing can be determined according to the light reflection        which the light receiver captures.

The light-reflecting surface can be in the form of a surface of aseparate component, or in the form of an integrated surface of acomponent of the washing handling device, e.g. the tub. As the housing,for example the housing of the washing handling device, or a componentarranged within the washing handling device, can be used. It is alsopossible to attach the sensor arrangement to the tub, and thelight-reflecting surface to the housing of the washing handling device.

According to the invention, it can also be provided that thechangeable-position component is a tub in which a washing drum isrotatably carried, the tub being suspended in the housing so that itsposition can change. In relation to this, according to the invention itis possible that the tub is carried in the housing by means of at leastone passive or actively controllable damper, and in the latter case thedamper characteristic can be adjusted according to the captured relativeposition of the drum receptacle in the housing.

Alternatively, according to the invention, it can be provided that thechangeable-position component is a membrane which is prestressed by aspring and can be shifted in a housing, and which closes and seals apressure chamber in the housing, it being possible to capture therelative position of the membrane relative to the housing according tothe captured light reflection, taking account of the compression stateof the spring. According to the present pressure in the pressurechamber, the membrane is deflected to a greater or lesser extent againstthe spring force, compared with a pressure-free initial state. Thisdeflection is captured on the basis of the light reflection. Takingaccount of the spring characteristic, in particular the spring constant,and the known area of the membrane, conclusions can thus be drawn aboutthe pressure in the pressure chamber. This pressure can give informationabout the present fullness of the tub with water or lye, for example.

According to another embodiment of the invention, it can be providedthat the changeable-position component is a force sensor which isprestressed by a spring. Again, on the basis of the captured lightreflection and the compression of the spring associated with it, andtaking account of the spring characteristic, conclusions can be drawnabout the force acting on the spring. In this way, for example, it ispossible to determine what quantity of washing was introduced into thedrum, and/or how much water or lye is in the tub.

According to the magnitudes which are captured using the deviceaccording to the invention, the operating mode, e.g. the spin speed, thequantity of water to be fed in, the damper characteristic of theactively controllable damper, etc. of the washing handling device can beadjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained using an example, on the basis of theattached figures, of which:

FIG. 1 is a schematic drawing of a washing machine according to theinvention;

FIG. 2 is an enlarged schematic view of the measuring device accordingto FIG. 1;

FIG. 3 is an enlarged view of a measuring device according to theinvention, to capture pressure;

FIG. 4 is an enlarged view of a measuring device according to theinvention, to capture force;

FIG. 5 is a diagram to explain the operation of the force measuringdevice according to FIG. 4, and

FIG. 6 is a schematic representation to explain the measuring processwith an embodiment according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In FIG. 1, a washing machine according to the invention is shownschematically, and identified as a whole by 10. This comprises a housing12, in which a tub 14 is displaceably suspended. For suspension, foursprings 16, 18, 20, 22, which hold the tub 14 elastically in the upperhousing region, are used. The tub 14 is carried by four dampers 24, 26,28, 30 in the lower housing region. The dampers 24, 26, 28, 30 can bepassive or actively controllable, and in the latter case, of activecontrol, their damper characteristic can be changed.

The washing machine 10 also comprises a measuring device 32 to capturethe position of the tub 14 relative to the housing 12. This measuringdevice 32 is shown enlarged in FIG. 2.

It comprises three pairs of light source and light receiver, namely afirst pair 34, 36, a second pair 38, 40 and a third pair 42, 44. Each ofthe light sources 34, 38, 42 emits a light beam 46, 48. These lightbeams are scattered and reflected at the scattering reflecting surfaces50, 52 facing the pairs of light source and light receiver, so thatdepending on the present distance between the scattering reflectingsurface and the light receiver 36, 40, 44, at each light receiver 36,40, 44 reflected (scattered) light can be captured with a definiteintensity which represents the present distance. The third scatteringreflecting surface, facing the pair 42, 44, is not shown in the figure.If the distance between light receiver 36, 40, 44 and associatedscattering reflecting surface changes, the light intensity which thelight receiver 36, 40, 44 captures also changes.

With the measuring arrangement 32, any deflections of the tub 14, thescattering reflecting surfaces 50, 52 and the third scatteringreflecting surface (not drawn) which are permanently coupled to itrelative to the module 60, which is fixed in position and carries thepairs of light source and light receiver, can be captured in real time.In other words, with the measuring arrangement 32 the present position(along all three spatial axes) of the tub 14 in the housing 12 of thewashing machine 10 can be captured. This optical capture is to a largeextent free of interference effects such as mechanical wear,electromagnetic interference fields, etc. If necessary, the deflectionalong the spatial axes X, Y and Z shown in FIG. 2 can be measuredsequentially, i.e. in a time sequence, so that even mutual interferenceeffects of the individual pairs of light source and light receiver canbe prevented. Alternatively, light which is polarised specifically foreach measurement direction can be used.

To improve the measurement result, according to the invention opticalcomponents such as lenses, screens or filters can be used.

FIG. 3 shows the principle of the measuring device according to theinvention, as used with a pressure sensor 62. The pressure sensor 62comprises a housing 64 with a pressure connection, inlet and/or outlet66. In the housing 64, a movable membrane 68, which has an area 70 ofwhich the shape is stable, said area 70 being attached to the housing 64via flexible areas 72, 74 so that it is sealed but displaceable, isarranged. The membrane 68 delimits a pressure chamber 76. The membrane68 is prestressed into an initial position via a compression spring 78into the pressure chamber 76. On its side facing away from the pressurechamber 76, it has a scattering reflecting surface 78.

On the side of the membrane 68 facing away from the pressure chamber 76,on the housing 64 a module 80 with a pair of light source and lightreceiver is arranged, and as described in relation to FIG. 2, it emits alight beam to the membrane, and receives scattered reflected light fromthe membrane. The distance d, which is given by the measurement resultwhich the module 80 determines regarding the light intensity, describesthe present compression state of the compression spring 78 relative toan initial state D. From this, taking account of the known springconstant c of the compression spring 78, according to Hooke's Law(F=c*[D−d]) the spring force F which is exerted on the compressionspring 78 can be calculated directly.

Once the movable area A of the membrane 68 is also known, the pressure pin the pressure chamber 76 can be calculated directly from thedetermined spring force F and the relation p=F/A.

With the solution according to the invention shown in FIG. 3, acontactless pressure sensor, which can be used inexpensively in washinghandling devices such as washing machines or driers, can be implementedin a technically simple way.

FIG. 4 shows another embodiment of the invention, but implemented as aforce sensor. In a housing 82, a measuring rod 84 is displaceablyreceived. In the housing 82, fixed in the housing, a first measuringsensor 86 and a second measuring sensor 88 are attached, each measuringsensor having a pair of light source and light receiver. A reflectingsurface carrier 90, which has two reflecting surfaces 92, 94, is coupledto the measuring rod 84. They are essentially parallel to each other,but offset by a distance x. The reflecting surface carrier 90 isprestressed via a compression spring 96 into an initial position.Depending on the deflection of the reflecting surface carrier 90relative to the housing 82, the result at the measuring sensors 86, 88is different intensities of the reflected light at the reflectingsurfaces 92, 94, so that conclusions can be drawn about the presentposition of the reflecting surface carrier 90 and thus of the measuringrod 84.

Again, on the basis of Hooke's Law (F=c*[D−d]) the spring force F whichis exerted on the compression spring 96 can be calculated directly. Forexample, if the measuring rod 84 is coupled to the tub 14, it ispossible to determine from this with what quantity/mass of washingor/and lye the tub 14 is filled.

On the basis of the reflecting surfaces 92, 94, which are offset fromeach other, the result is two different curves K₁, K₂ for theintensities I of reflected light, as measured by the measuring sensors86, 88. This provides the possibility of a plausibility check, since themeasurement results can always be compared with each other. This alsoprovides the possibility of calibration and compensation of themeasuring system taking account of the known offset x, e.g. bycoefficient formation and/or normalisation. The evaluation can also besimplified in this way. The light intensity I, as is known, falls withthe square of the travelled distance x (I˜1/x²). In the case of quotientformation, instead of quadratic relations linear ones are obtained,which simplifies the computational evaluation.

Finally, FIG. 6 shows a possible arrangement of a measuring device 100according to the invention in a washing machine, for 2 axes. Areflecting surface carrier 102, with reflecting surfaces 104, 106arranged perpendicularly to each other, is attached in a way not shownto a tub, via fixing strips 108, 110. A measuring sensor arrangement112, with two measuring sensors 114, 116 arranged orthogonally to eachother, emits a pencil of rays 118. This is reflected and scattered atthe reflecting surface 104, as shown by the pencil of rays 120.Depending on the distance d, the result is a light intensity, which iscaptured by the sensor arrangement 114. In this way, the presentrelative position between the fixed measuring sensor arrangement 112 andthe reflecting surface carrier 102, which is movable with the tub, canbe determined. This measuring principle can be extended directly for thethird spatial axis.

Although the preferred embodiments of the present invention have beendescribed herein, the above description is merely illustrative. Furthermodification of the invention herein disclosed will occur to thoseskilled in the respective arts and all such modifications are deemed tobe within the scope of the invention as defined by the appended claims.

What is claimed is:
 1. A sensor device to measure a force or pressure ina washing handling apparatus, the sensor device comprising: a lightsource; a light receiver; a light-reflecting surface that reflects lightemitted by the light source toward the light receiver; and one or morespring elements that biases the light-reflecting surface into apredefined initial position with respect to the light source and thelight receiver, wherein the light-reflecting surface is disposed to bedisplaceable with respect to the light source and the light receiver inresponse to application of an external force or pressure against aresetting force of the one or more spring elements to thereby change adistance of the light-reflecting surface relative to the light sourceand the light receiver, wherein the device is configured to determinethe applied external force or pressure based on reflected light capturedby the light receiver.
 2. The sensor device of claim 1 wherein the oneor more spring elements include a compression spring disposed to becompressed in response to application of the external force or pressure.3. The sensor device of claim 1 wherein the device is configured todetermine the applied external force or pressure based on the reflectedlight captured by the light receiver and further based on a springconstant of the one or more spring elements and Hooke's law.
 4. Thesensor device of claim 1 wherein the reflected light captured by thelight receiver decreases in a measured intensity as the applied externalforce increases.
 5. The sensor device of claim 1 further comprising: ahousing accommodating the light source and the light receiver and havingan interior; a measuring rod extending from the housing interior tooutside the housing and disposed to be displaceable with respect to thehousing, the measuring rod having an end portion located in the housinginterior; and a reflecting surface carrier coupled to the end portion ofthe measuring rod and carrying the light-reflecting surface.
 6. Thesensor device of claim 5 wherein the measuring rod is coupled to a tub.7. The sensor device of claim 1 wherein the reflecting surface is ascattering reflecting surface.
 8. The sensor device of claim 1 whereinthe light source is configured to emit polarized light.
 9. The sensordevice of claim 1 wherein the light source is one of a light-emittingdiode, a laser diode and an infrared light source.
 10. The sensor deviceof claim 1 wherein the light receiver is one of a phototransistor, aphotodiode and a passively operated light-emitting diode.
 11. The sensordevice of claim 1 wherein the light source and the light receiver arecombined next to each other in one module.
 12. A washing machinecomprising: a machine housing; a tub suspended in the machine housing; aplurality of springs to support the tub elastically with respect to themachine housing; a sensor device to measure a force exerted on at leastone of the plurality of springs, the sensor device comprising: a lightsource; a light receiver; a light-reflecting surface that reflects lightemitted by the light source toward the light receiver, thelight-reflecting surface disposed to be elastically displaceable withrespect to the light source and the light receiver in response toapplication of a force acting upon the at least one of the plurality ofsprings against a resetting force thereof, to thereby change a distanceof the light-reflecting surface relative to the light source and thelight receiver, wherein the device is configured to determine theapplied force based on reflected light captured by the light receiver.13. The washing machine of claim 12 wherein the sensor device includes:a sensor housing accommodating the light source and the light receiverand having an interior; a measuring rod extending from the interior tooutside the sensor housing and disposed to be displaceable with respectto the sensor housing, the measuring rod having an end portion locatedin the interior; and a reflecting surface carrier coupled to the endportion of the measuring rod and carrying the light-reflecting surface,wherein the measuring rod is coupled to the tub.